On and after October 2, 1992, the Bureau of Reclamation may invite non-Federal entities involved in cost sharing arrangements for the development of water projects to participate in contract negotiation and source selection proceedings without invoking provisions of chapter 10 of title 5: Provided, That such non-Federal participants shall be subject to the provisions of chapter 21 of title 41 and to the conflict of interest provisions appearing at 18 U.S.C. 201 et seq. (1988).